In recent years, as fuel consumption restrictions and exhaust emission regulations for automobiles, etc., are augmented, there is demand for atomization of fuel sprays that are sprayed from fuel injection valves. Because of that, in conventional fuel injection valves, a spraying aperture that sprays fuel is constituted by: a first cylindrical aperture; and a second cylindrical aperture that is disposed consecutively downstream from the first cylindrical aperture. The second cylindrical aperture has a larger diameter than the first cylindrical aperture, and is inclined at a predetermined angle relative to a central axis of the first cylindrical aperture (see Patent Literature 1, for example).
In other conventional fuel injection valves, a guiding portion that guides fuel flow toward inner circumferential inner wall surfaces of a spraying aperture is formed on an inlet-side opening edge of the spraying aperture at least near an outer peripheral side. Because of that, fuel that reaches a vicinity of the outer peripheral inner wall surface of the inlet-side opening edge of the spraying aperture is subjected to a guiding action of the guiding portion and is led to the inner circumferential inner wall surfaces of the spraying aperture. Thus, because the spraying aperture is inclined away from a central axis of a spraying aperture plate, the fuel that reaches the inner circumferential inner wall surfaces of the spraying aperture is formed into a liquid film by flowing over the inner wall surfaces of the spraying aperture, and is atomized by spraying (see Patent Literature 2, for example).
In addition, in conventional fluid injection nozzles, a spraying aperture plate is constituted by two pieces, i.e., an upper spraying aperture plate and a lower spraying aperture plate. Upstream spraying apertures are disposed on the upper spraying aperture plate so as to be parallel to a plate thickness direction thereof. In addition, tapered downstream spraying apertures are disposed on the lower spraying aperture plate. Aperture diameters d2 of the upstream spraying apertures are less than or equal to inlet-side aperture diameters d3 of the downstream spraying apertures. Thus, improvements in atomization can be achieved by the downstream spraying apertures while forming the upstream spraying apertures, which are easy to machine, precisely to ensure flow rate precision (see Patent Literature 3, for example).